1. Technical Field
The present disclosure relates generally to orthopedic surgery and in particular to devices and prosthesis for stabilizing and fixing the bones and joints of the body.
2. Background of Related Art
It is a common surgical procedure to stabilize and fix bones and bone fragments in a particular spatial relationship with fixation devices to correct the location of skeletal components due to injury or disease. This can be accomplished by using a number of fixation devices such as bone pins, anchors, or screws placed in bone across a discontinuity (e.g., a fracture) in the bone, bone fragments, adjacent vertebrae, or joints. These fixation devices can be connected by a rod to maintain a desired spatial relationship. In some cases, these fixation devices may be permanently implanted. In other cases, these fixation devices may be implanted only as a temporary means of stabilizing or fixing the bones or bone fragments. It is also common that fixation devices that are intended to be permanently implanted require subsequent modifications as the dynamics of a patient's condition warrant.
Spinal fixation devices are widely employed in surgical processes for correcting spinal injuries and diseases. These devices commonly employ longitudinal link rods (e.g., spinal rods) secured to vertebrae by spinal bone fixation fasteners such as pedicle screws, hooks and others.
Many conventional devices for locking a spinal rod to a hook or screw do not offer the needed flexibility to allow the spinal rod to be easily connected to misaligned adjacent vertebrae. In addition, the spinal rod may excessively rotate and/or axially translate when being positioned within the screw, making the spinal rod securement even more difficult. Some effort has been made to provide a multi-planar screw; however, even for devices that have attempted to address the issue of securing spinal rods to misaligned vertebrae, there remains the problem of providing such a multi-planar screw and spinal rod combination that can be easily locked and unlocked in position without the need to exert additional torque to the device or force on the patient. Furthermore, it would be desirous to provide a multi-planar screw and spinal rod combination having increased friction therebetween, such that when the spinal rod and the multi-planar screw are engaged, axial and/or rotational movement of the spinal rod is prevented. This will facilitate the spinal rod securement.